Cargo Hold Ventilation, Dew Point & Sweat Risk Tool
Compare cargo-hold and outside-air dew points, screen for cargo sweat
and ship sweat, assess outside-air drying potential and review a
configurable three-degree ventilation comparison. Advanced mode
models changing voyage conditions and identifies the periods with
the highest condensation exposure.
Dew Point
Hold air vs outside-air moisture conditions
Sweat Risk
Cargo surface and ship-steel condensation margins
Ventilation Screen
Drying direction, three-degree comparison and moisture-transfer potential
Hold & Outside Conditions
Use measured temperatures and relative humidity where available.
All temperatures are entered in degrees Celsius.
°C
%
°C
%
Cargo & Ship Surface Temperatures
°C
Cargo sweat becomes possible when the cargo surface is at or
below the dew point of air contacting the cargo.
°C
Used only for the configurable three-degree comparison.
°C
Use measured or vessel-specific estimated internal steel-surface
temperature where possible.
°C
Context only. It is not used as a substitute for entered steel temperature.
°C
A positive margin below this user-entered buffer is flagged as
close to the dew point.
°C
Optional Ventilation Moisture Model
This estimates gross moisture-transfer potential only. It assumes
the entered air conditions remain constant during the ventilation period.
m³
air changes/hour
hours
Voyage Condition Profile
Add changing voyage conditions. Each row compares hold-air dew point,
outside-air dew point, cargo temperature and ship-steel temperature.
Hours are used to calculate time-weighted risk exposure.
Condition
Hours
Outside °C
Outside RH %
Hold °C
Hold RH %
Cargo °C
Steel °C
Advanced Risk & Ventilation Assumptions
°C
°C
°C
m³
air changes/hour
% of each period
Used only for the theoretical moisture-transfer estimate.
Dew Point & Sweat Risk Results
Single-condition cargo-hold analysis
Enter hold conditions
Enter cargo-hold temperature, relative humidity and surface
temperatures to calculate dew point and condensation margins.
Overall Sweat Risk
N/A
Cargo and ship-surface condensation screen
Ventilation Moisture Direction
N/A
Based on outside vs hold moisture conditions
Hold Dew Point
N/A
Outside Dew Point
N/A
Dew Point Advantage
N/A
Cargo Sweat Margin
N/A
Ship Sweat Margin
N/A
Hold Absolute Humidity
N/A
Outside Absolute Humidity
N/A
Three-Degree Comparison
N/A
Cargo Risk Hours
N/A
Ship Risk Hours
N/A
Outside Air Drier Hours
N/A
Gross Moisture Transfer
N/A
Sweat Risk Screen
Cargo Sweat
N/A
Ship Sweat
N/A
Dew Point Comparison
N/A
Three-Degree Comparison
N/A
Voyage Condition Results
Advanced mode
Condition
Hours
Hold DP
Outside DP
Cargo Margin
Ship Margin
Outside Air
Risk
Ventilation & Moisture Summary
Dew Point & Risk Summary
Model approach:
dew point is calculated from entered dry-bulb temperature and
relative humidity using a Magnus-type psychrometric approximation.
Cargo-sweat margin equals cargo-surface temperature minus hold-air
dew point. Ship-sweat margin equals cargo-side steel temperature
minus hold-air dew point. A margin at or below zero indicates that
condensation is physically possible under the entered conditions.
Outside-air drying potential is screened by comparing outside and
hold dew points and absolute humidity. The optional ventilation
model estimates gross moisture-transfer potential from the
absolute-humidity difference, hold free-air volume, air-change
rate and entered ventilation duration.
Planning estimate only.
Actual cargo-hold ventilation decisions depend on cargo type,
hygroscopic behavior, cargo temperature distribution, moisture content,
voyage climate, precipitation, sea spray, hold construction, insulation,
ventilation arrangement, hatch condition, weather-tight integrity,
charterer instructions, ship procedures and cargo-specific carriage
requirements. Surface temperatures may vary materially within a hold.
The three-degree comparison shown here is a configurable operational
screen only and is not a substitute for cargo-specific procedures.
Do not use this tool as the sole basis for ventilation, fumigation,
gas-safety, enclosed-space or cargo-care decisions.
